The present invention belongs to the field of methods and apparatuses relating to a wireless office system, and in particular to a wireless office system which is associated with a voice mail system providing voice mail services to one or more mobile stations having subscriptions in the wireless office system.
A PBX (Private Branch Exchange) is a local telephony switching system which interconnects a number of fixed phones, typically in an office or similar. The PBX enables the introduction of a local numbering plan which makes it possible to perform calls between the fixed phones connected to the PBX using local short (4-5 digit) numbers. The marginal costs associated with setting up calls between the fixed phones connected to the PBX is also very low, since connections are set up in the PBX without using an outside telephone network such as a PSTN (Public Switched Telephone Network), i.e. a conventional fixed telephone network.
Furthermore, the PBX is capable of performing various telephone management functions, such as integrating a voice mail system having voice mailboxes associated with the fixed phones connected to the PBX (see for example U.S. Pat. No. 5,561,703; or U.S. Pat. No. 5,388,151). If a call is made to one of the fixed phones connected to the PBX and a subscriber associated with the fixed phone does not answer, then the call is forwarded to the voice mail system, which plays a recorded so called greeting message to a calling party. The greeting message requests the calling party to leave a voice mail message, which will be recorded in a voice mailbox associated with the called fixed phone. When a message has been recorded in the voice mailbox, a small packet of informationxe2x80x94a message waiting indicator MWI (also known as a voice mail notification)xe2x80x94is sent from the voice mail system, via the PBX, to the called fixed phone. The MWI normally contains information about the number of the calling party, a voice mail index and, if known, the name of the calling party. The fixed phone is arranged for indicating the receipt of the MWI, for example by flashing a light or by presenting information relating to the MWI on a display. The gain of receiving a MWI is clear, since users of the fixed phones must not continuously check whether they have new voice mail messages in the voice mail system.
Today there is an increasing interest in wireless communications, for example mobile (cellular) telephony or mobile data transfer. So called wireless office systems (WOS) have therefore been developed in order to incorporate mobile stations, e.g. mobile telephones, mobile communicators or mobile computers having radio communication capabilities, into the local numbering plan. The WOS comprises a number of radio nodes, commonly known as radio heads. The radio heads are arranged for performing functions that are similar to the functions performed by radio base stations in a PLMN (Public Land Mobile Network). The radio heads are thus arranged for providing radio communication coverage in different parts of the office (or other location) where the local numbering plan is to be implemented. Mobile stations, when being present in the coverage area of the radio heads, are able to communicate with the radio heads over a radio interface. The WOS further comprises a radio control system, which controls the radio traffic between the mobile stations and the radio heads, and a switching system, which provide the necessary switching functions of the WOS. The WOS is normally connected to the PBX by means of a PRI (primary rate interface). With the WOS, it is therefore possible, using a local short number, to make a call to a mobile station, having a subscription in the WOS, from a fixed phone connected to the PBX or from a mobile station being in the coverage area of the radio heads. It is also possible, using a local short number, to make a call from a mobile station being in the coverage area of the radio heads to one of the fixed phones connected to the PBX. The marginal costs for making these calls are also very low, since the connections are set up in the WOS and, when appropriate, in the PBX. The WOS can also be used on it own without being connected to a PBX.
When a voice mail system is integrated with the PBX, it is not unusual that the voice mail system is also shared with the WOS that is connected with the PBX. One or more mobile stations, having subscriptions in the WOS, will then have associated voice mailboxes in the voice mail system. However, a drawback with having a shared voice mail system is that not all PRIs are able to transfer MWIs, and therefore it is not always possible to send MWIs from the voice mail system to the mobile stations having subscriptions in the WOS.
The present invention relates to a wireless office system providing wireless communication services to a predetermined number of mobile stations having subscriptions in the wireless office system. One or more of the mobile stations also have associated voice mailboxes in a voice mail system which is associated with but not included in the wireless office system.
The present invention addresses the problem of enabling determination in the wireless office system of when voice mail messages for users of the mobile stations are received at the voice mail system.
In short, the above stated problem is solved according to the following. The duration(s) of greeting message(s) associated with the voice mail system and the or each mobile station having an associated voice mailbox in the voice mail system is/are measured. The connection times to the voice mail system are measured when calls for the mobile stations are forwarded to the voice mail system from the wireless office system. By comparing the duration(s) of the greeting message(s) with the measured connection times, it is determined whether voice mail messages have been received.
The main object of the present invention is thus to enable determination in a wireless office system of when voice mail messages for users of the mobile stations are received at the voice mail system. The present invention includes methods, devices and systems relating to the above stated object.
The above stated problem can be solved more specifically according exemplifying embodiments of the invention. For example, in one exemplifying embodiment, the wireless office system is connected to a private branch exchange, and the voice mail system is shared between the wireless office system and the private branch exchange.
A main advantage of the present invention, in addition to solving the above stated problem, is that the invention provides the possibility to send message waiting indicators to the mobile stations, even if it is not possible to send message waiting indicators from the voice mail system to the wireless office system.